The current user can not access the LXD server which is required for the Ubuntu SDK. Make sure the user is part of the lxd group and restart the IDE.

running from /usr/bin/ubuntu-sdk-ide:

The current user can not access the LXD server which is required for the Ubuntu SDK.
Make sure the user is part of the lxd group and restart the IDE.
./ubuntu-sdk-ide: line 6: 8601 Segmentation fault (core dumped) $BINDIR/qtcreator -platformtheme appmenu-qt5 ${1+"$@"}

---
Xubuntu 16.04, fish shell, SDK 1.266~0ubuntu1~0xenial from ubuntu-sdk-team/ppa,
I am in lxd group on my PC.

# lxd init
error: Unable to talk to LXD: Get http://unix.socket/1.0: dial unix /var/lib/lxd/unix.socket: connect: connection refused

$ ls -lh /var/lib/lxd/unix.socket
srw-rw---- 1 root lxd 0 Sep 18 15:03 /var/lib/lxd/unix.socket=

# service lxd restart
A dependency job for lxd.service failed. See 'journalctl -xe' for details.

I've attached file with trimmed "journalctl -xe" output which I hope contains informations about problem.

run sudo ubuntu-sdk from terminal.

The problem here is that your user for some reason can not access the LXD server.
You maybe need to relogin after installing the SDK for the first time, if that does not
help there is a misconfiguration with LXD that blocks your user from accessing it.

1. check if your user is part of the lxd group, if not add it
2. check if you can access lxd with the upstream tools: lxc list

If 2. does not work the problem is somewhere in the LXD configuration itself.

"sudo ubuntu-sdk" displays same information

1.I'm in lxd group,
2. lxc list displays "Connection refused; is LXD running?"

Ok so if lxc can not access your server, the LXD installation itself is broken.

Check the access rights on the lxd socket:
 ls -la /var/lib/lxd/unix.socket

If your user can not access this socket that would be the problem.
I'd suggest do remove lxd and delete all configuration/data it did write to disk.

Should be in /var/lib/lxd. But remove the lxd package first and make sure that your
homedir is not mounted anymore under /var/lib/lxd.

Hello, i am a basic user; when tryif to open ubuntu sdk ide it says "The current user can not access the LXD server which is required for the Ubuntu SDK.
Make sure the user is part of the lxd group and restart the IDE."

What do i do?

Never mind; i just typed sudo ubuntu-sdk

But, before starting a new project i have to create kits but when i try create a kit this appears " Creating image with: framework: ubuntu-sdk-15.04 arch: amd64
Fixing possible container permission problems....
All containers are accessible. Checking for and removing broken devices....
Fixing possible DRI devices....
Adding device /dev/dri/card0 to desktop: unix-char [path=dev/dri/card0 gid=44]
Device /dev/dri/card0 added to desktop Fixing possible NVidia issues....
Adding device tmp to desktop: disk [source=/tmp path=/tmp recursive=true]
Device tmp added to desktop
0 0
error: Registering root is not possible
---Task exited with errors, please check the output---

any ideas?

The User-Group changes for LXD takes sometimes effect after a relog of the current User.
So relog and try again to start.

As a new user this is very discouraging for me, silly error like this right from the start.
At this point I am not sure I am running Ubuntu_SDK or Ubuntu_SDK_IDE.
It also seems too complex for new guy who wants to start with C++ "Hello word".
It took some searching to find it.

The answer here worked for me:

http://askubuntu.com/questions/835571/unable-to-run-ubuntu-sdk-cannot-access-lxd-server